A 3D Geometry-Based Non-Stationary MIMO Channel Model for RIS-Assisted Communications

Recently, reconfigurable intelligent surface (RIS) has drawn much attention due to its capability of improving coverage and communication performance. In this paper, a geometric RIS-assisted multiple-input multiple-output channel model is proposed for fixed-to-mobile (F2M) communications based on a three-dimensional cylinder model. The receiver is regarded as in motion, and the time-varying angles and propagation distances are derived to describe non-stationary channels. Based on the proposed channel model, the effect of RIS on spacetime correlation function is investigated. The results can be used to evaluate and optimize the performance of RIS-assisted F2M communication systems.